ALPHA-HELICAL CRF9-41 PREVENTS ANXIOGENIC-LIKE EFFECT OF NPY Y-1 RECEPTOR ANTAGONIST BIBP3226 IN RATS

WE reported previously that the neuropeptide Y (NPY) Y-1 receptor anta gonist, nylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine amide (BIBP 3226) has an anxiogenic-like effect in the elevated plus maze test in rats. In this study we investigated the effect of the corticotropin-re leasing factor (CRF) receptor antagonist, alpha-helical-CRF9-41 (alpha -h-CRF) on this response. BIBP3226 (5 mu g, i.c.v.) induced an anxioge nic-like effect, which was blocked by pretreatment with alpha-h-CRF at a concentration (1 mu g, i.c.v.) which alone failed to affect the ele vated plus maze performance. Thus, the anxiogenic effect of a selectiv e Y-1 receptor blocker was prevented by the blockade of CRF receptors, suggesting antagonistic effects of endogenous NPY and CRF in shaping the response to novelty.